Systems and methods for delivering bone fill material and controlling the temperature thereof

ABSTRACT

The present invention relates in certain embodiments to systems and methods for use in osteoplasty procedures, such as vertebral compression fractures. One system for injecting a bone fill material includes a container carrying a bone fill material. An elongated introducer configured for introduction into a vertebral body is coupleable to the container to allow a flow of the bone fill material therethrough. A cooling mechanism is coupled to the container and is configured to cool the bone fill material in the container to extend the working time of the bone fill material. One method for treating a vertebra includes providing a bone fill material, cooling the bone fill material to stall the polymerization of the bone fill material, heating the bone fill material to accelerate the polymerization of the bone fill material and delivering the bone fill material into a vertebral body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 60/762,611, filed Jan. 27, 2006, and of U.S. ProvisionalApplication No. 60/788,755, filed Apr. 3, 2006, the entire contents ofwhich are hereby incorporated by reference and should be considered apart of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in certain embodiments to medical devicesfor osteoplasty treatment procedures, such as vertebral compressionfractures. More particularly, embodiments of the invention relate tosystems and methods for injecting bone fill material into a bone andcontrolling the temperature of the bone fill material.

2. Description of the Related Art

Osteoporotic fractures are prevalent in the elderly, with an annualestimate of 1.5 million fractures in the United States alone. Theseinclude 750,000 vertebral compression fractures (VCFs) and 250,000 hipfractures. The annual cost of osteoporotic fractures in the UnitedStates has been estimated at $13.8 billion. The prevalence of VCFs inwomen age 50 and older has been estimated at 26%. The prevalenceincreases with age, reaching 40% among 80-year-old women. Medicaladvances aimed at slowing or arresting bone loss from aging have notprovided solutions to this problem. Further, the population affectedwill grow steadily as life expectancy increases. Osteoporosis affectsthe entire skeleton but most commonly causes fractures in the spine andhip. Spinal or vertebral fractures also cause other serious sideeffects, with patients suffering from loss of height, deformity andpersistent pain which can significantly impair mobility and quality oflife. Fracture pain usually lasts 4 to 6 weeks, with intense pain at thefracture site. Chronic pain often occurs when one vertebral level isgreatly collapsed or multiple levels are collapsed.

Postmenopausal women are predisposed to fractures, such as in thevertebrae, due to a decrease in bone mineral density that accompaniespostmenopausal osteoporosis. Osteoporosis is a pathologic state thatliterally means “porous bones”. Skeletal bones are made up of a thickcortical shell and a strong inner meshwork, or cancellous bone, of withcollagen, calcium salts and other minerals. Cancellous bone is similarto a honeycomb, with blood vessels and bone marrow in the spaces.Osteoporosis describes a condition of decreased bone mass that leads tofragile bones which are at an increased risk for fractures. In anosteoporosis bone, the sponge-like cancellous bone has pores or voidsthat increase in dimension making the bone very fragile. In young,healthy bone tissue, bone breakdown occurs continually as the result ofosteoclast activity, but the breakdown is balanced by new bone formationby osteoblasts. In an elderly patient, bone resorption can surpass boneformation thus resulting in deterioration of bone density. Osteoporosisoccurs largely without symptoms until a fracture occurs.

Vertebroplasty and kyphoplasty are recently developed techniques fortreating vertebral compression fractures. Percutaneous vertebroplastywas first reported by a French group in 1987 for the treatment ofpainful hemangiomas. In the 1990's, percutaneous vertebroplasty wasextended to indications including osteoporotic vertebral compressionfractures, traumatic compression fractures, and painful vertebralmetastasis. Vertebroplasty is the percutaneous injection of PMMA(polymethylmethacrylate) into a fractured vertebral body via a trocarand cannula. The targeted vertebrae are identified under fluoroscopy. Aneedle is introduced into the vertebrae body under fluoroscopic control,to allow direct visualization. A bilateral transpedicular (through thepedicle of the vertebrae) approach is typical but the procedure can bedone unilaterally. The bilateral transpedicular approach allows for moreuniform PMMA infill of the vertebra.

In a bilateral approach, approximately 1 to 4 ml of PMMA is used on eachside of the vertebra. Since the PMMA needs to be is forced into thecancellous bone, the techniques require high pressures and fairly lowviscosity cement. Since the cortical bone of the targeted vertebra mayhave a recent fracture, there is the potential of PMMA leakage. The PMMAcement contains radiopaque materials so that when injected under livefluoroscopy, cement localization and leakage can be observed. Thevisualization of PMMA injection and extravasion are critical to thetechnique—and the physician terminates PMMA injection when leakage isevident. The cement is injected using syringes to allow the physicianmanual control of injection pressure.

Kyphoplasty is a modification of percutaneous vertebroplasty.Kyphoplasty involves a preliminary step consisting of the percutaneousplacement of an inflatable balloon tamp in the vertebral body. Inflationof the balloon creates a cavity in the bone prior to cement injection.The proponents of percutaneous kyphoplasty have suggested that highpressure balloon-tamp inflation can at least partially restore vertebralbody height. In kyphoplasty, some physicians state that PMMA can beinjected at a lower pressure into the collapsed vertebra since a cavityexists, when compared to conventional vertebroplasty.

The principal indications for any form of vertebroplasty areosteoporotic vertebral collapse with debilitating pain. Radiography andcomputed tomography must be performed in the days preceding treatment todetermine the extent of vertebral collapse, the presence of epidural orforaminal stenosis caused by bone fragment retropulsion, the presence ofcortical destruction or fracture and the visibility and degree ofinvolvement of the pedicles.

Leakage of PMMA during vertebroplasty can result in very seriouscomplications including compression of adjacent structures thatnecessitate emergency decompressive surgery. See “Anatomical andPathological Considerations in Percutaneous Vertebroplasty andKyphoplasty: A Reappraisal of the Vertebral Venous System”, Groen, R. etal, Spine Vol. 29, No. 13, pp 1465-1471 2004. Leakage or extravasion ofPMMA is a critical issue and can be divided into paravertebral leakage,venous infiltration, epidural leakage and intradiscal leakage. Theexothermic reaction of PMMA carries potential catastrophic consequencesif thermal damage were to extend to the dural sac, cord, and nerveroots. Surgical evacuation of leaked cement in the spinal canal has beenreported. It has been found that leakage of PMMA is related to variousclinical factors such as the vertebral compression pattern, and theextent of the cortical fracture, bone mineral density, the interval frominjury to operation, the amount of PMMA injected and the location of theinjector tip. In one recent study, close to 50% of vertebroplasty casesresulted in leakage of PMMA from the vertebral bodies. See Hyun-Woo Doet al, “The Analysis of Polyrnethylmethacrylate Leakage afterVertebroplasty for Vertebral Body Compression Fractures”, Jour. ofKorean Neurosurg. Soc. Vol. 35, No. 5 (May 2004) pp. 478-82,(http://www.jkns.or.kr/htm/abstract.asp?no=0042004086).

Another recent study was directed to the incidence of new VCFs adjacentto the vertebral bodies that were initially treated. Vertebroplastypatients often return with new pain caused by a new vertebral bodyfracture. Leakage of cement into an adjacent disc space duringvertebroplasty increases the risk of a new fracture of adjacentvertebral bodies. See Am. J. Neuroradiol. Feb. 25, 2004 (2):175-80. Thestudy found that 58% of vertebral bodies adjacent to a disc with cementleakage fractured during the follow-up period compared with 12% ofvertebral bodies adjacent to a disc without cement leakage.

Another life-threatening complication of vertebroplasty is pulmonaryembolism. See Bernhard, J. et al, “Asymptomatic diffuse pulmonaryembolism caused by acrylic cement: an unusual complication ofpercutaneous vertebroplasty”, Ann. Rheum. Dis. 2003;62:85-86. The vaporsfrom PMMA preparation and injection also are cause for concern. SeeKirby, B, et al., “Acute bronchospasm due to exposure topolymethylmethacrylate vapors during percutaneous vertebroplasty”, Am.J. Roentgenol. 2003; 180:543-544.

In both higher pressure cement injection (vertebroplasty) andballoon-tamped cementing procedures (kyphoplasty), the methods do notprovide for well controlled augmentation of vertebral body height. Thedirect injection of bone cement simply follows the path of leastresistance within the fractured bone. The expansion of a balloon appliesalso compacting forces along lines of least resistance in the collapsedcancellous bone. Thus, the reduction of a vertebral compression fractureis not optimized or controlled in high pressure balloons as forces ofballoon expansion occur in multiple directions.

In a kyphoplasty procedure, the physician often uses very high pressures(e.g., up to 200 or 300 psi) to inflate the balloon which crushes andcompacts cancellous bone. Expansion of the balloon under high pressuresclose to cortical bone can fracture the cortical bone, typically theendplates, which can cause regional damage to the cortical bone with therisk of cortical bone necrosis. Such cortical bone damage is highlyundesirable as the endplate and adjacent structures provide nutrientsfor the disc.

Kyphoplasty also does not provide a distraction mechanism capable of100% vertebral height restoration. Further, the kyphoplasty balloonsunder very high pressure typically apply forces to vertebral endplateswithin a central region of the cortical bone that may be weak, ratherthan distributing forces over the endplate.

There is a general need to provide bone cements and methods for use intreatment of vertebral compression fractures that provide a greaterdegree of control over introduction of cement and that provide betteroutcomes. Embodiments of the present invention meet this need andprovide several other advantages in a novel and nonobvious manner.

SUMMARY OF THE INVENTION

Certain embodiments of the invention provide systems and methods fortreating bone, such as a vertebra by delivering bone fill material intothe interior of the vertebra. One embodiment utilizes Rf energy or otherenergy sources to controllably elevate the temperature of bone fillmaterial flows as the flows exit the working end of an introducer. Acomputer controller controls the bone fill material flow parameters andenergy delivery parameters for selectively polymerizing the fillmaterial inflow plume to thereby control the direction of flow and theultimate geometry of a flowable, in-situ hardenable bone fill material.The system and method further includes means for sealing tissue in theinterior of a vertebra to prevent migration of monomers, fat or emboliinto the patient's bloodstream.

In one embodiment, a cooling system is provided for cooling bone fillmaterial, e.g. in a remote container or injection cannula, forcontrolling and extending the working time of bone fill material inosteoplasty procedures. In another embodiment, the bone fill materialinjection system includes a thermal energy emitter for warming a chilledbone fill material, e.g. in the distal end of the injector, or forapplying sufficient energy to accelerate the polymerization of the bonefill material, thereby increasing the viscosity of the bone cement.

In another embodiment, a controller is provided to control allparameters of bone fill material injection. For example, the controllercan control bone fill material inflow parameters from, for example, ahydraulic mechanism. The controller can also control the sensing systemand energy delivery parameters for selectively heating tissue orpolymerizing bone fill material at both the interior and exterior of theintroducer. The workload on a physician during an osteoplasty procedurecan thus advantageously be reduced.

In one embodiment, a bone fill material injection system is providedcomprising a container carrying a bone fill material therein. The systemalso comprises an elongated introducer configured for introduction intoa vertebral body, the introducer coupleable to the container andconfigured to allow a flow of the bone fill material therethrough. Thesystem also comprises a cooling mechanism coupled to the container andconfigured to cool the bone fill material in the container to extend aworking time thereof.

In another embodiment, a system for injecting a bone fill material isprovided comprising a container carrying a bone fill material. Thesystem also comprises an elongated introducer configured forintroduction into a vertebral body, the introducer coupleable to thecontainer and configured to allow a flow of bone fill materialtherethrough. The system also comprises means for cooling the bone fillmaterial within the container to extend a working time of the bone fillmaterial.

In still another embodiment, a method for treating a vertebra of a humanbody is provided comprising providing a bone fill material. The methodalso comprises cooling the bone fill material to stall thepolymerization time of the bone fill material and heating the bone fillmaterial to accelerate the polymerization of the bone fill material. Themethod also comprises delivering the bone fill material into a vertebralbody.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the invention and to see how it may becarried out in practice, some preferred embodiments are next described,by way of non-limiting examples only, with reference to the accompanyingdrawings, in which like reference characters denote correspondingfeatures consistently throughout similar embodiments in the attacheddrawings.

FIG. 1 is a schematic side view of a spine segment showing a vertebrawith a compression fracture and an introducer, in accordance with oneembodiment disclosed herein.

FIG. 2A is a schematic perspective view of a system for treating bone,in accordance with one embodiment.

FIG. 2B is a schematic perspective view of a working end of theintroducer of FIG. 2A.

FIG. 3A is a schematic perspective view of a working end of anintroducer, in accordance with one embodiment.

FIG. 3B is a schematic perspective view of a working end of anintroducer, in accordance with another embodiment.

FIG. 3C is a schematic perspective view of a working end of anintroducer, in accordance with yet another embodiment.

FIG. 4 is a schematic cross-sectional side view of one embodiment of aworking end of a probe, in accordance with one embodiment.

FIG. 5A is a schematic side view of an introducer inserted into avertebral body and injecting flowable fill material into the vertebralbody.

FIG. 5B is a schematic side view of the introducer in FIG. 5A injectinga relatively high viscosity volume of flowable fill material into thevertebral body, in accordance with one embodiment of the presentinvention.

FIG. 6 is a schematic perspective view of a system for treating bone, inaccordance with another embodiment.

FIG. 7A is a schematic sectional view of a fill material, in accordancewith one embodiment.

FIG. 7B is a schematic sectional view of a fill material, in accordancewith another embodiment.

FIG. 8A is a schematic perspective view of a system for treating bone,in accordance with another embodiment.

FIG. 8B is a schematic perspective view of the system in FIG. 8A,injecting an additional volume of fill material into a vertebral body.

FIG. 9A is a schematic cross-sectional view of one step in a method fortreating bone, in accordance with one embodiment.

FIG. 9B is a schematic cross-sectional view of another step in a methodfor treating bone, in accordance with one embodiment.

FIG. 9C is a schematic cross-sectional view of still another step in amethod for treating bone, in accordance with one embodiment.

FIG. 10A is a schematic cross-sectional view of a step in a method fortreating bone, in accordance with another embodiment.

FIG. 10B is a schematic cross-sectional view of another step in a methodfor treating bone, in accordance with another embodiment.

FIG. 11A is a schematic perspective view of a system for treating bone,in accordance with another embodiment.

FIG. 11B is a schematic perspective view of the system in FIG. 11A,applying energy to a fill material.

FIG. 12 is a schematic perspective view of a system for treating bone,in accordance with another embodiment.

FIG. 13 is a schematic view of another embodiment of a bone cementdelivery system together with an aspiration source.

FIG. 14A is a sectional view of a working end of an introducer as inFIG. 13 showing the orientation of a cement injection port in avertebra.

FIG. 14B is a sectional view of the working end of FIG. 14A showing aninitial inflow of bone cement.

FIG. 14C is a sectional view of the working end of FIG. 14B showing anadditional inflow of bone cement to reduces a vertebral fracture.

FIG. 15A is a sectional view of a vertebra depicting a first mode ofoperation wherein an initial flow of bone cement is provided underselected flow parameters that allow cement interdigitation intocancellous bone.

FIG. 15B is a sectional view of a vertebra similar to FIG. 15A depictinga second mode of operation wherein cement flows are provided in a highacceleration pulse that disallows cement interdigitation into cancellousbone.

FIG. 16 is a sectional schematic view of another embodiment of a bonecement delivery system.

FIG. 17 is a schematic perspective view of another embodiment of a bonecement delivery system for treating osteoporotic bone or a fracturedvertebra.

FIG. 18A is a sectional view of a vertebra showing one step of a methodfor delivering bone cement to a vertebra, in accordance with oneembodiment.

FIG. 18B is a sectional view of the vertebra of FIG. 18A showing anotherstep of the method for delivering bone cement to a vertebra.

FIG. 18C is a sectional view similar to FIGS. 18A-18B showing anotherstep of the method for delivering bone cement to a vertebra.

FIG. 19 is a perspective schematic view of another embodiment of a bonecement delivery system.

FIG. 20 is a perspective schematic view of another embodiment of aninjector with a thin wall sleeve and a sensor system.

FIG. 21 is a perspective schematic view of another embodiment of a bonecement delivery system.

FIG. 22 is a perspective schematic view of another embodiment of a bonecement delivery system.

FIG. 23A is a sectional view of one embodiment of a bone cement injectorhaving an energy emitter.

FIG. 23B is a sectional view of another embodiment of a bone cementinjector having an energy emitter.

FIG. 24 is a perspective schematic view of another embodiment of a bonecement delivery system.

FIG. 25 is a sectional schematic view of another embodiment of a bonecement injector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Definitions

“Bone fill material, infill material or composition” includes itsordinary meaning and is defined as any material for infilling a bonethat includes an in-situ hardenable material, such as bone cement. Thefill material also can include other “fillers” such as filaments,microspheres, powders, granular elements, flakes, chips, tubules and thelike, autograft or allograft materials, as well as other chemicals,pharmacological agents or other bioactive agents.

“Flowable material” includes its ordinary meaning and is defined as amaterial continuum that is unable to withstand a static shear stress andresponds with an irrecoverable flow (a fluid)—unlike an elastic materialor elastomer that responds to shear stress with a recoverabledeformation. Flowable material includes fill material or composites thatinclude a fluid (first) component and an elastic or inelastic material(second) component that responds to stress with a flow, no matter theproportions of the first and second component, and wherein the aboveshear test does not apply to the second component alone.

An “elastomer” includes its ordinary meaning and is defined as materialhaving to some extent the elastic properties of natural rubber whereinthe material resumes or moves toward an original shape when a deformingforce is removed.

“Substantially” or “substantial” mean largely but not necessarilyentirely. For example, substantially may mean about 10% to about99.999%, about 25% to about 99.999% or about 50% to about 99.999%.

“Osteoplasty” includes its ordinary meaning and means any procedurewherein fill material is delivered into the interior of a bone.

“Vertebroplasty” includes its ordinary meaning and means any procedurewherein fill material is delivered into the interior of a vertebra.

Systems and Methods of Infill Material Delivery and Energy Application

For the purpose of understanding the principles of the invention,reference will now be made to the embodiments illustrated in thedrawings and accompanying text that describe the invention. Furtherdetails on systems and methods for the delivery of bone cement can befound in U.S. patent application Ser. No. 11/165,652, filed Jun. 24,2005, now U.S. Pub. No. 2006-0122623; U.S. application Ser. No.11/196,045, filed Aug. 2, 2005, now U.S. Pub. No. 2006-0122624; U.S.application Ser. No. 11/208,448, filed Aug. 20, 2005, now U.S. Pub. No.2006-0122621; and U.S. application Ser. No. 11/209,035, filed Aug. 22,2005, now U.S. Pub. No. 2006-0122625, the entire contents of which arehereby incorporated by reference and should be considered a part of thisspecification.

FIG. 1 illustrates one embodiment of the invention for treating a spinesegment in which a vertebral body 90 has a wedge compression fractureindicated at 94. In one embodiment, the systems and methods are directedto safely introducing a bone fill material into cancellous bone of thevertebra without extravasion of fill material in unwanted directions (i)to prevent micromotion in the fracture for eliminating pain, and (ii) tosupport the vertebra and increase vertebral body height. Further,systems and methods are provided for sealing cancellous bone (e.g.,blood vessels, fatty tissues etc.) in order to prevent monomers, fat,fill material and other emboli from entering the venous system duringtreatment.

FIG. 1 illustrates a fractured vertebra and bone infill system 100 whichincludes probe 105 having a handle end 106 extending to an elongatedintroducer 110A and working end 115A, shown in FIG. 2A. The introduceris shown introduced through pedicle 118 of the vertebra for accessingthe osteoporotic cancellous bone 122 (See FIG. 2A). The initial aspectsof the procedure are similar to conventional percutaneous vertebroplastywherein the patient is placed in a prone position on an operating table.The patient is typically under conscious sedation, although generalanesthesia is an alternative. The physician injects a local anesthetic(e.g., 1% Lidocaine) into the region overlying the targeted pedicle orpedicles as well as the periosteum of the pedicle(s). Thereafter, thephysician uses a scalpel to make a 1 to 5 mm skin incision over eachtargeted pedicle. Thereafter, the introducer 110A is advanced throughthe pedicle into the anterior region of the vertebral body, whichtypically is the region of greatest compression and fracture. Thephysician confirms the introducer path posterior to the pedicle, throughthe pedicle and within the vertebral body by anteroposterior and lateralX-Ray projection fluoroscopic views. The introduction of infill materialas described below can be imaged several times, or continuously, duringthe treatment depending on the imaging method.

It should be appreciated that the introducer also can be introduced intothe vertebra from other angles, for example, along axis 113 through thewall of the vertebral body 114 as in FIG. 1 or in an anterior approach(not shown). Further, first and second cooperating introducers can beused in a bilateral transpedicular approach. Additionally, any mechanismknown in the art for creating an access opening into the interior of thevertebral body 90 can be used, including open surgical procedures.

Now referring to FIGS. 2A and 2B, the end of introducer 110A is shownschematically after being introduced into cancellous bone 122 with aninflow of fill material indicated at 120. The cancellous bone can be inany bone, for example in a vertebra. It can be seen that the introducer110A and working end 115A comprise a sleeve or shaft that is preferablyfabricated of a metal having a flow channel 118 extending therethroughfrom the proximal handle end 106 (see FIG. 1). In one embodiment, theintroducer shaft is a stainless steel tube 123 having an outsidediameter ranging between about 3.5 and 4.5 mm, but other dimensions arepossible. As can be seen in FIG. 2A and 3A, the flow channel 118 canterminate in a single distal opening or outlet 124 a in the working end115A, or there can be a plurality of flow outlets or ports 124 barranged angularly about the radially outward surface of the working end115A, as shown in FIG. 3B. The outlets in the working end thus allow fordistal or radial ejection of fill material, or a working end can have acombination of radial and distal end outlets. As can be seen in FIG. 3C,the distal end of working end 115A also can provide an angled distal endoutlet 124 c for directing the flow of fill material from the outlet byrotating the working end 115A.

In FIGS. 2A and 2B, it can be seen that system 100 includes a remoteenergy source 125A and a controller 125B that are operatively coupled toan energy emitter 128 in the working end 115A of the introducer 110A forapplying energy to the fill material 120 contemporaneous with andsubsequent to ejection of the fill material 120 from the working end115A. In one preferred embodiment, the energy source 125A is aradiofrequency (Rf) source known in the art that is connected to atleast one electrode (132 a and 132 b in FIG. 2B) in contact withinjected fill material 120, which preferably carries a radiosensitivecomposition therein. It is equally possible to use other remote energysources and emitters 128 in the working end 115A which fall within thescope of the invention, such as (i) an electrical source coupled to aresistive heating element in the working end, (ii) a light energy source(coherent or broadband) coupled to an optical fiber or other lightchannel terminating in the working end; (iii) an ultrasound sourcecoupled to an emitter in the working end; or a (iv) microwave sourcecoupled to an antenna in the working end. In still another embodiment,the energy source 125A can be a magnetic source. The fill material 120preferably includes an energy-absorbing material or anenergy-transmitting material that cooperates with energy delivered froma selected energy source. For example, the energy-absorbing orenergy-transmitting material can be a radiosensitive or conductivematerial for cooperating with an Rf source, chromophores for cooperatingwith a light source, ferromagnetic particles for cooperating with amagnetic source, and the like. In one embodiment, the fill material 120can include a composition having an energy-absorbing property and anenergy-transmitting property for cooperating with the remote energysource 125A. For example, the composition can absorb energy from theremote energy source 125A for polymerizing the composite or transmitenergy for heating tissue adjacent to the composite.

As can be understood from FIGS. 2A and 2B, the exemplary introducer 110Ais operatively coupleable to a source 145 of bone fill material 120together with a pressure source or mechanism 150 that operates on thesource of fill material 145 to deliver the fill material 120 through theintroducer 110A into a bone (see arrows). The pressure source 150 cancomprise any type of pump mechanism, such as a piston pump, screw pumpor other hydraulic pump mechanism. In FIG. 2B, the pump mechanism isshown as a piston or plunger 152 that is slidable in the channel 118 ofintroducer 110A. In one embodiment, the pressure source 150 includes acontroller 150B that controls the pressure applied by the pressuresource 150. For example, where the pressure source 150 is a piston pumpor screw pump that is motor driven, the controller 150B can adjust themotor speed to vary the pressure applied by the pressure source 150 tothe inflow of the bone fill material 120. In one embodiment, thecontroller 150B also controls the volume of the bone fill material 120that is introduced to a bone portion. In another embodiment, thecontroller 150B, or a separate controller, can also control the volumeof bone fill material 120 introduced into the bone portion. For example,the controller 150B can operate a valve associated with the bone fillsource 145 to selectively vary the valve opening, thus varying thevolume of bone fill material 120 introduced to the bone portion.

As shown in FIGS. 2A and 2B, the introducer 110A preferably has anelectrically and thermally insulative interior sleeve 154 that definesthe interior flow channel 118. The sleeve can be any suitable polymerknown in the art such as PEEK, Teflon™ or a polyimide. As can be seen inFIG. 2B, interior sleeve 154 carries conductive surfaces that functionas energy emitter 128, and more particularly comprise spaced apartopposing polarity electrodes 132 a and 132 b. The electrodes 132 a and132 b can have any spaced apart configuration and are disposed about thedistal termination of channel 118 or about the surfaces of outlet 124 a.The electrode configuration alternatively can include a first electrodein the interior of channel 118 and a second electrode on an exterior ofintroducer 110A. For example, the metallic sleeve 123 or a distalportion thereof can comprise one electrode. In a preferred embodiment,the electrodes 132 a and 132 b are connected to the Rf energy source125A and controller 125B by an electrical cable 156 with (+) and (−)electrical leads 158 a and 158 b therein that extend through theinsulative sleeve 154 to the opposing polarity electrodes. In oneembodiment, the electrical cable 156 is detachably coupled to the handleend 106 of probe 105 by male-female plug (not shown). The electrodes 132a and 132 b can be fabricated of any suitable materials known to thoseskilled in the art, such as stainless steels, nickel-titanium alloys andalloys of gold, silver platinum and the like.

In one embodiment, not shown, the working end 115A can also carry anysuitable thermocouple or temperature sensor for providing data tocontroller 125B relating to the temperature of the fill material 120during energy delivery. One or more thermocouples may be positioned atthe distal tip of the introducer, or along an outer surface of theintroducer and spaced from the distal end, in order to providetemperature readings at different locations within the bone. Thethermocouple may also be slideable along the length of the introducer.In another embodiment, the working end can have at least one side port(not shown) in communication with a coolant source, the port configuredto provide the coolant (e.g., saline) therethrough into the cancellousbone 122 to cool the cancellous bone in response to a temperaturereading from the temperature sensor.

Now turning to FIG. 4, the sectional view of working end 115Aillustrates the application of energy to fill material 120 as it isbeing ejected from outlet 124 a. The fill material 120 in the proximalportion of channel 118 is preferably a low viscosity flowable materialsuch as a two-part curable polymer that has been mixed (e.g., PMMA) butwithout any polymerization having, for example, a viscosity of less thanabout 50,000 cps. Such a low viscosity fill material allows forsimplified lower pressure injection through the introducer 110A.Further, the system allows the use of a low viscosity fill material 120which can save great deal of time for the physician.

In a preferred embodiment, it is no longer necessary to wait for thebone cement to partly polymerize before injection. As depicted in FIG.4, energy delivery at selected parameters from electrodes 132 a and 132b to fill material 120 contemporaneous with its ejection from outlet 124a selectively alters a property of fill material indicated at 120′. Inone embodiment, the altered flow property is viscosity. For example, theviscosity of the fill material 120′ can be increased to a higherviscosity ranging from about 100,000 cps or more, 1,000,000 cps or more,to 2,000,000 cps or more. In another embodiment, the flow property isYoung's modulus. For example, the Young's modulus of the fill material120′ can be altered to be between about 10 kPa and about 10 GPa. Instill another embodiment, the flow property can be one of durometer,hardness and compliance.

Preferably, the fill material 120 carries a radiosensitive compositionfor cooperating with the Rf source 125A, as further described below. Ata predetermined fill material flow rate and at selected Rf energydelivery parameters, the altered fill material 120′ after ejection cancomprise an increased viscosity material or an elastomer. At yet anotherpredetermined fill material flow rate and at other Rf energy deliveryparameters, the altered fill material 120′ after ejection can comprise asubstantially solid material. In the system embodiment utilized forvertebroplasty as depicted in FIGS. 2A and 5B, the controller 125B isadapted for delivering Rf energy contemporaneous with the selected flowrate of fill material 120 to provide a substantially high viscosity fillmaterial 120′ that is still capable of permeating cancellous bone. Inother osteoplasty procedures such as treating necrosis of a bone, thesystem controller 125B can be adapted to provide much harder fillmaterial 120′ upon ejection from outlet 124 a. Further, the system canbe adapted to apply Rf energy to the fill material continuously, or in apulse mode or in any selected intervals based on flow rate, presets, orin response to feedback from temperature sensors, impedance measurementsor other suitable signals known to those skilled in the art.

In one embodiment, the controller 125B includes algorithms for adjustingpower delivery applied by the energy source 125A. For example, in oneembodiment the controller 125B includes algorithms for adjusting powerdelivery based on impedance measurements of the fill material 120′introduced to the bone portion. In another embodiment, the controller125B includes algorithms for adjusting power delivery based on thevolume of bone fill material 120 delivered to the bone portion. In stillanother embodiment, the controller 125B includes algorithms foradjusting power delivery based on the temperature of the bone fillmaterial 120′ introduced to the bone portion.

FIGS. 5A and 5B are views of a vertebra 90 that are useful forexplaining relevant aspects of one embodiment of the invention whereinworking end 110A is advanced into the region of the fracture 94 in thecancellous bone 122. FIG. 5A indicates system 100 being used to injectflow material 120′ into the vertebra with the flow material having aviscosity similar to conventional vertebroplasty or kyphoplasty, forexample having the consistency of toothpaste. FIG. 5A depicts thesituation wherein high pressure injection of a low viscosity materialcan simply follow paths of least resistance along a recent fractureplane 160 to migrate anteriorly in an uncontrolled manner. The migrationof fill material could be any direction, including posteriorly towardthe spinal canal or into the disc space depending on the nature of thefracture.

FIG. 5B illustrates system 100 including actuation of the Rf source 125Aby the controller 125B to contemporaneously heat the fill material toeject altered fill material 120′ with a selected higher viscosity intocancellous bone 122, such as the viscosities described above. With aselected higher viscosity, FIG. 5B depicts the ability of the system toprevent extravasion of fill material and to controllably permeate andinterdigitate with cancellous bone 122, rather than displacingcancellous bone, with a plume 165 that engages cortical bone vertebralendplates 166 a and 166 b. The fill material broadly engages surfaces ofthe cortical endplates to distribute pressures over the endplates. In apreferred embodiment, the fill material controllably permeatescancellous bone 122 and is ejected at a viscosity adequate tointerdigitate with the cancellous bone 122. Fill material with aviscosity in the range of between about 100,000 cps to 2,000,000 cps maybe ejected, though even lower or higher viscosities may also besufficient. The Rf source may selectively increase the viscosity of thefill material by about 10% or more as it is ejected from the introducer115A. In other embodiments, the viscosity may be increased by about 20%,50%, 100%, 500% or 1000% or more.

Still referring to FIG. 5B, it can be understood that continued inflowsof high viscosity fill material 120′ and the resultant expansion ofplume 165 will apply forces on endplates 166 a and 166 b to at leastpartially restore the vertebral height of the vertebra 90. It should beappreciated that the working end 115A can be translated axially betweenabout the anterior third of the vertebral body and the posterior thirdof the vertebral body during the injection of fill material 120′, aswell as that the working end 115A, which can be any of the typesdescribed above and shown in FIGS. 3A-3C, can be rotated.

FIG. 6 is a schematic view of an alternative embodiment of system 100wherein the Rf source 125A and the controller 125B are configured tomultiplex energy delivery to provide additional functionality. In onemode of operation, the system functions as described above and depictedin FIGS. 4 and 5B to alter flow properties of flowable fill material120′ as it is ejected from working end 115A. As can be seen in FIG. 6,the system further includes a return electrode or ground pad 170. Thusthe system 100 can be operated in a second mode of operation whereinelectrodes 132 a and 132 b (see FIG. 2B) are switched to a commonpolarity (or the distal portion of sleeve 123 can comprise such anelectrode) to function in a mono-polar manner in conjunction with theground pad 170. This second mode of operation advantageously createshigh energy densities about the surface of plume 165 to therebyohmically heat tissue at the interface of the plume 165 and the bodystructure.

In FIG. 6, the ohmically heated tissue is indicated at 172, wherein thetissue effect is coagulation of blood vessels, shrinkage of collagenoustissue and generally the sealing and ablation of bone marrow,vasculature and fat within the cancellous bone. The Rf energy levels canbe set at a sufficiently high level to coagulate, seal or ablate tissue,with the controller delivering power based, for example, on impedancefeedback which will vary with the surface area of plume 165. Ofparticular interest, the surface of plume 165 is used as an electrodewith an expanding wavefront within cancellous bone 122. Thus, thevasculature within the vertebral body can be sealed by controlled ohmicheating at the same time that fill material 120′ is permeating thecancellous bone. Within the vertebral body are the basivertebral(intravertebral) veins which are paired valveless veins connecting withnumerous venous channels within the vertebra (pars spongiosa/red bonemarrow). These basivertebral veins drain directly into the externalvertebral venous plexus (EVVP) and the superior and inferior vena cava.The sealing of vasculature and the basivertebral veins is particularlyimportant since bone cement and monomer embolism has been frequentlyobserved in vertebroplasty and kyphoplasty cases (see “Anatomical andPathological Considerations in Percutaneous Vertebroplasty andKyphoplasty: A Reappraisal of the Vertebral Venous System”, Groen, R. etal, Spine Vol. 29, No. 13, pp 1465-1471 2004). It can be thus understoodthat the method of using the system 100 creates and expands a“wavefront” of coagulum that expands as the plume 165 of fill materialexpands. The expandable coagulum layer 172, besides sealing the tissuefrom emboli, contains and distributes pressures of the volume of infillmaterial 120′ about the plume surface.

The method depicted in FIG. 6 provides an effective means for sealingtissue via ohmic (Joule) heating. It has been found that passive heattransfer from the exothermic reaction of a bone cement does notadequately heat tissue to the needed depth or temperature to sealintravertebral vasculature. In use, the mode of operation of the system100 in a mono-polar manner for ohmically heating and sealing tissue canbe performed in selected intervals alone or in combination with thebi-polar mode of operation for controlling the viscosity of the injectedfill material.

In general, one aspect of the vertebroplasty or osteoplasty method inaccordance with one of the embodiments disclosed herein allows forin-situ control of flows of a flowable fill material, and moreparticularly comprises introducing a working end of an introducer sleeveinto cancellous bone, ejecting a volume of flowable fill material havinga selected viscosity and contemporaneously applying energy (e.g., Rfenergy) to the fill material from an external source to thereby increasethe viscosity of at least portion of the volume to prevent fillextravasion. In a preferred embodiment, the system increases theviscosity by about 20% or more. In another preferred embodiment, thesystem increases the viscosity by about 50% or more.

In another aspect of one embodiment of a vertebroplasty method, thesystem 100 provides means for ohmically heating a body structure aboutthe surface of the expanding plume 165 of fill material to effectivelyseal intravertebral vasculature to prevent emboli from entering thevenous system. The method further provides an expandable layer ofcoagulum about the infill material to contain inflow pressures anddistribute further expansion forces over the vertebral endplates. In apreferred embodiment, the coagulum expands together with at least aportion of the infill material to engage and apply forces to endplatesof the vertebra.

Of particular interest, one embodiment of fill material 120 as used inthe systems described herein (see FIGS. 2A, 4, 5A-5B and 6) is acomposite comprising an in-situ hardenable or polymerizable cementcomponent 174 and an electrically conductive filler component 175 in asufficient volume to enable the composite to function as a dispersableelectrode (FIG. 6). In one type of composite, the conductive fillercomponent is any biocompatible conductive metal. In another type ofcomposite, the conductive filler component is a form of carbon. Thebiocompatible metal can include at least one of titanium, tantalum,stainless steel, silver, gold, platinum, nickel, tin, nickel titaniumalloy, palladium, magnesium, iron, molybdenum, tungsten, zirconium,zinc, cobalt or chromium and alloys thereof. The conductive fillercomponent has the form of at least one of filaments, particles,microspheres, spheres, powders, grains, flakes, granules, crystals,rods, tubules, nanotubes, scaffolds and the like. In one embodiment, theconductive filler includes carbon nanotubes. Such conductive fillercomponents can be at least one of rigid, non-rigid, solid, porous orhollow, with conductive filaments 176 a illustrated in FIG. 7A andconductive particles 176 b depicted in FIG. 7B.

In a preferred embodiment, the conductive filler comprises choppedmicrofilaments or ribbons of a metal as in FIG. 7A that have a diameteror a cross-section dimension across a major axis ranging between about0.0005″ and 0.01″. The lengths of the microfilaments or ribbons rangefrom about 0.01″ to 0.50″. The microfilaments or ribbons are ofstainless steel or titanium and are optionally coated with a thin goldlayer or silver layer that can be deposited by electroless platingmethods. Of particular interest, the fill material 120 of FIG. 7A has anin situ hardenable cement component 174 than has a first low viscosityand the addition of the elongated microfilament conductive fillercomponent 175 causes the composite 120 to have a substantially highapparent viscosity due to the high surface area of the microfilamentsand its interaction with the cement component 174. In one embodiment,the microfilaments are made of stainless steel, plated with gold, andhave a diameter of about 12 microns and a length of about 6 mm. Theother dimensions provided above and below may also be utilized for thesemicrofilaments.

In another embodiment of bone fill material 120, the conductive fillercomponent comprises elements that have a non-conductive core portionwith a conductive cladding portion for providing electrosurgicalfunctionality. The non-conductive core portions are selected from thegroup consisting of glass, ceramic or polymer materials. The claddingcan be any suitable conductive metal as described above that can bedeposited by electroless plating methods.

In any embodiment of bone fill material that uses particles,microspheres, spheres, powders, grains, flakes, granules, crystals orthe like, such elements can have a mean dimension across a principalaxis ranging from about 0.5 micron to 2000 microns. More preferably, themean dimension across a principal axis range from about 50 microns to1000 microns. It has been found that metal microspheres having adiameter of about 800 microns are useful for creating conductive bonecement that can function as an electrode.

In one embodiment, a conductive filler comprising elongatedmicrofilaments wherein the fill material has from about 0.5% to 20%microfilaments by weight. More preferably, the filaments are from about1% to 10% by weight of the fill material. In other embodiments whereinthe conductive filler comprises particles or spheres, the conductivefiller can comprise from about 5% of the total weight to about 80% ofthe weight of the material.

In an exemplary fill material 120, the hardenable component can be anyin-situ hardenable composition such as at least one of PMMA, monocalciumphosphate, tricalcium phosphate, calcium carbonate, calcium sulphate orhydroxyapatite.

Referring now to FIGS. 8A and 8B, an alternative method is shown whereinthe system 100 and method are configured for creating asymmetries inproperties of the infill material and thereby in the application offorces in a vertebroplasty. In FIG. 8A, the pressure mechanism 150 isactuated to cause injection of an initial volume or aliquot of fillmaterial 120′ that typically is altered in viscosity in working end 115Aas described above—but the method encompasses flows of fill materialhaving any suitable viscosity. The fill material 120′ is depicted inFIGS. 8A and 8B as being delivered in a unilateral transpedicularapproach, but any extrapedicular posterior approach is possible as wellas any bilateral posterior approach. The system in FIGS. 8A-8B againillustrates a vertical plane through the fill material 120′ that flowsunder pressure into cancellous bone 122 with expanding plume orperiphery indicated at 165. The plume 165 has a three dimensionalconfiguration as can be seen in FIG. 8B, wherein the pressurized flowmay first tend to flow more horizontally that vertically. One embodimentof the method of the invention includes the physician translating theworking end 115A of the introducer 110A slightly and/or rotating theworking end 115A so that flow outlets 124 a are provided in a selectedradial orientation. In a preferred embodiment, the physicianintermittently monitors the flows under fluoroscopic imaging asdescribed above.

FIG. 8B depicts a contemporaneous or subsequent energy-delivery step ofthe method wherein the physician actuates the Rf electrical source 125Aand controller 125B to cause Rf current delivery from the at least oneelectrode emitter 128 to cause ohmic (Joule) heating of tissue as wellas internal heating of the inflowing fill material 120′. In thisembodiment, the exterior surface of sleeve 123 is indicated as electrodeor emitter 128 with the proximal portion of introducer 110A having aninsulator coating 178. The Rf energy is preferably applied in an amountand for a duration that coagulates tissue as well as alters aflowability property of surface portions 180 of the initial volume offill material proximate the highest energy densities in tissue.

In one preferred embodiment, the fill material 120 is particularlydesigned to create a gradient in the distribution of conductive fillerwith an increase in volume of material injected under high pressure intocancellous bone 122. This aspect of the method in turn can be usedadvantageously to create asymmetric internal heating of the fill volume.In this embodiment, the fill material 120 includes a conductive fillerof elongated conductive microfilaments 176 a (FIG. 7A). The filamentsare from about 2% to 5% by weight of the fill material, with thefilaments having a mean diameter or mean sectional dimension across aminor axis ranging between about 0.001″ and 0.010″ and a length rangingfrom about 1 mm to about 10 mm, more preferably about 1 mm to 5 mm. Inanother embodiment, the filaments have a mean diameter or a meandimension across a minor axis ranging between about 1 micron and 500microns, more preferably between about 1 micron and 50 microns, evenmore preferably between about 1 micron and 20 microns. It has been foundthat elongated conductive microfilaments 176 a result in resistance toflows thereabout which causes such microfilaments to aggregate away fromthe most active media flows that are concentrated in the center of thevertebra proximate to outlet 124 a. Thus, the conductive microfilaments176 a attain a higher concentration in the peripheral or surface portion180 of the plume which in turn will result in greater internal heatingof the fill portions having such higher concentrations of conductivefilaments. The active flows also are controlled by rotation ofintroducer 110A to eject the material preferentially, for examplelaterally as depicted in FIG. 8A and 8B rather that vertically. Thehandle 106 of the probe 105 preferably has markings to indicate therotational orientation of the outlets 124 b.

FIG. 8A depicts the application of Rf energy in a monopolar mannerbetween electrode emitter 128 and ground pad 170, which thus causesasymmetric heating wherein surface portion 180 heating results ingreater polymerization therein. As can be seen in FIG. 8A, the volume offill material thus exhibits a gradient in a flowability property, forexample with surface region 180 having a higher viscosity than inflowingmaterial 120′ as it is ejected from outlet 124 a. In one embodiment, thegradient is continuous. Such heating at the plume periphery 165 cancreate an altered, highly viscous surface region 180. This step of themethod can transform the fill material to have a gradient in flowabilityin an interval of about 5 seconds to 500 seconds with surface portion180 being either a highly viscous, flowable layer or an elastomer thatis expandable. In preferred embodiments, the interval of energy deliveryrequired less than about 120 seconds to alter fill material to aselected asymmetric condition. In another aspect of the invention, theRf energy application for creating the gradient in flowability also canbe optimized for coagulating and sealing adjacent tissue.

The combination of the viscous surface portion 180 and the tissuecoagulum 172 may function as an in-situ created stretchable, butsubstantially flow-impervious, layer to contain subsequent high pressureinflows of fill material. Thus, the next step of the method is depictedin FIG. 8B which includes injecting additional fill material 120′ underhigh pressure into the interior of the initial volume of fill material120 that then has a highly viscous, expandable surface. The viscous,expandable surface desirably surrounds cancellous bone so that thesubsequent injection of fill material can expand the fill volume toapply retraction forces on the vertebra endplates 166 a and 166 b toprovide vertical jacking forces, distracting cortical bone, forrestoring vertebral height, as indicated by the arrows in FIG. 8B. Thesystem can generate forces capable of breaking callus in cortical boneabout a vertebral compression fracture when the fracture is less thancompletely healed.

In one embodiment, the method includes applying Rf energy to createhighly viscous regions in a volume of fill material and thereafterinjecting additional fill material 120 to controllably expand the fillvolume and control the direction of force application. The scope of themethod further includes applying Rf energy in multiple intervals orcontemporaneous with a continuous flow of fill material. The scope ofthe method also includes applying Rf energy in conjunction with imagingmeans to prevent unwanted flows of the fill material. The scope of theinvention also includes applying Rf energy to polymerize and acceleratehardening of the entire fill volume after the desired amount of fillmaterial has been injected into a bone.

In another embodiment, the method includes creating Rf current densitiesin selected portions of the volume of fill material 120 to createasymmetric fill properties based on particular characteristics of thevertebral body. For example, the impedance variances in cancellous boneand cortical bone can be used to create varied Rf energy densities infill material 120 to create asymmetric properties therein. Continuedinjection of fill material 120 are thus induced to apply asymmetricretraction forces against cortical endplates 166 a and 166 b, whereinthe flow direction is toward movement or deformation of the lowerviscosity portions and away from the higher viscosity portions. In FIGS.9A-9C, it can be seen that in a vertebroplasty, the application of Rfenergy in a mono-polar manner as in FIG. 6 naturally and preferentiallycreates more highly viscous, deeper “altered” properties in surfaces ofthe lateral peripheral fill volumes indicated at 185 and 185′ and lessviscous, thinner altered surfaces in the superior and inferior regions186 and 186′ of fill material 120. This effect occurs since Rf currentdensity is localized about paths of least resistance which arepredominantly in locations proximate to highly conductive cancellousbone 122 a and 122 b. The Rf current density is less in locationsproximate to less conductive cortical bone indicated at 166 a and 166 b.Thus, it can be seen in FIG. 9B that the lateral peripheral portions 185and 185′ of the first flows of fill material 120 are more viscous andresistant to flow and expansion than the thinner superior and inferiorregions. In FIG. 9C, the asymmetrical properties of the initial flows offill material 120 allows the continued flows to apply retraction forcesin substantially vertical directions to reduce the vertebral fractureand increase vertebral height, for example from VH (FIG. 9B) to VH′ inFIG. 9C.

FIGS. 10A and 10B are schematic views that further depict a methodcorresponding to FIGS. 9B and 9C that comprises expanding cancellousbone for applying retraction forces against cortical bone, e.g.,endplates of a vertebra in a vertebroplasty. As can be seen in FIG. 10A,an initial volume of flowable fill material 120 is injected intocancellous bone wherein surface region 180 is altered as described aboveto be highly viscous or to comprise and elastomer that is substantiallyimpermeable to interior flows but still be expandable. The surfaceregion 180 surrounds subsequent flows of fill material 120′ whichinterdigitate with cancellous bone. Thereafter, as shown in FIG. 10B,continued high pressure inflow into the interior of the fill materialthereby expands the cancellous bone 122 together with the interdigitatedfill material 120′. As can be seen in FIG. 10B, the expansion ofcancellous bone 122 and fill material 120′ thus applies retractionforces to move cortical bone endplates 166 a and 166 b. The method ofexpanding cancellous bone can be used to reduce a bone fracture such asa vertebral compression fracture and can augrnent or restore the heightof a fractured vertebra. The system thus can be used to support retractand support cortical bone, and cancellous bone. The method can alsorestore the shape of an abnormal vertebra, such as one damaged by atumor.

After utilizing system 100 to introduce, alter and optionally hardenfill material 120 as depicted in FIGS. 9A-9C and 10A-10B, the introducer110A can be withdrawn from the bone. Alternatively, the introducer 110Acan have a release or detachment structure indicated at 190 forde-mating the working end from the proximal introducer portion asdescribed in co-pending U.S. patent application Ser. No. 11/130,843,filed May 16, 2005, now U.S. Pub. No. 2006-0100706, the entirety ofwhich is hereby incorporated by reference and should be considered apart of this specification.

Another system 200 for controlling flow directions and for creatingasymmetric properties is shown in FIGS. 11A and 11B, wherein first andsecond introducers 110A and 110B similar to those described above areused to introduce first and second independent volumes 202 a and 202 bof fill material 120 in a bilateral approach. In this embodiment, thetwo fill volumes function as opposing polarity electrodes in contactwith electrodes 205 a and 205 b of the working ends. Current flowbetween the electrodes thus operates in a bi-polar manner with thepositive and negative polarities indicated by the (+) and (−) symbols.In this method, it also can be seen that the highest current densityoccurs in the three dimensional surfaces of volumes 202 a and 202 b thatface one another. This results in creating the thickest, high viscositysurfaces 208 in the medial, anterior and posterior regions and the least“altered” surfaces in the laterally outward regions. This method is wellsuited for preventing posterior and anterior flows and directingretraction forces superiorly and inferiorly since lateral flow arecontained by the cortical bone at lateral aspects of the vertebra. Thesystem can further be adapted to switch ohmic heating effects betweenthe bi-polar manner and the mono-polar manner described previously.

Now referring to FIG. 12, another embodiment is shown wherein atranslatable member 210 that functions as an electrode is carried byintroducer 110A. In a preferred embodiment, the member 210 is asuperelastic nickel titanium shape memory wire that has a curved memoryshape. The member 210 can have a bare electrode tip 212 with aradiopaque marking and is otherwise covered by a thin insulator coating.In FIG. 12, it can be seen that the introducer can be rotated and themember can be advanced from a port 214 in the working end 115A underimaging. By moving the electrode tip 212 to a desired location and thenactuating RF current, it is possible to create a local viscous orhardened region 216 of fill material 120. For example, if imagingindicates that fill material 120 is flowing in an undesired direction,then injection can be stopped and Rf energy can be applied to harden theselected location.

FIG. 13 illustrates another embodiment of the introducer 110A whichincludes a transition in cross-sectional dimension to allow fordecreased pressure requirements for introducing bone cement through thelength of the introducer 110A. In the embodiment of FIG. 13, theproximal handle end 106 is coupled to introducer 110A that has a largerdiameter proximal end portion 218 a that transitions to a smallerdiameter distal end portion 218 b configured for insertion into avertebral body. The distal end portion 218 b includes exterior threads220 for helical advancement and engagement in bone to prevent theintroducer 110A from moving proximally when cement is injected into avertebral body or other bone, for example to augment vertebral heightwhen treating a VCF. The bore that extends through the introducer 110Asimilarly transitions from larger diameter bore portion 224 a to smallerdiameter bore portion 224 b. The embodiment of FIG. 13 utilizes a boretermination or slot 225 in a sidewall of the working end 115A forejecting bone cement at a selected radial angle from the axis 226 of theintroducer for directing cement outflows within a vertebral body.

Still referring to FIG. 13, the introducer 110A is coupled to bonecement source 145 and pressure source 150 as described previously thatis controlled by controller 125B. Further, an energy source 125A (e.g.,Rf source) is coupled to an energy delivery mechanism in the working end115A for applying energy to a cement flow within bore 224 b. In theembodiment of FIG. 13, the introducer 110A can be fabricated of a strongreinforced plastic such a polymide composite with a sleeve electrode 228in bore 224 b and inward of the bore termination slot 225, similar toelectrode 128 depicted in FIG. 3A. The electrode 228 in FIG. 13 iscoupled to Rf source 125A for operating in a mono-polar manner incooperation with the return ground pad 170. The controller 125B again isoperatively connected to the Rf source 125A to adjust energy deliveryparameters in response to feedback from a thermocouple 235 in the bore124 b or in response to measuring impedance of the cement flow. In FIG.13, the controller 125B further is operationally connected to anaspiration source 240 that is coupled to a needle-like introducer sleeve242 that can be inserted into a bone to apply suction forces to theinterior of vertebra for relieving pressure in the vertebra and/orextracting fluids, bone marrow and the like that could migrate into thevenous system. The use of such an aspiration system will be describedfurther below.

In FIG. 13, the introducer 110A has a larger diameter bore 224 a thatranges from about 4 mm to 10 mm, and preferably is in the range of about5 mm to 6 mm. The smaller diameter bore 224 b can range from about 1 mmto 3 mm, and preferably is in the range of about 1.5 mm to 2.5 mm. Theexterior threads 220 can be any suitable height with single or dualflights configured for gripping cancellous bone. The thread height andlength of the reduced diameter section 218 b are configured forinsertion into a vertebra so that the port 225 can be anteriorly orcentrally located in the vertebral body. The working end 115A furthercarries a radiopaque marking 244 for orienting the radial angle of theintroducer and bore termination port 225. In FIG. 13, the radiopaquemarking 244 is elongated and surrounds port 225 in the introducersidewall. The handle 106 also carries a marking 245 for indicating theradial angle of port 225 to allow the physician to orient the port byobservation of the handle.

Now referring to FIGS. 14A-14C, the working end 115A of the introducerof FIG. 13 is shown after being introduced into cancellous bone 122 invertebra 90. FIG. 14A illustrates a horizontal sectional view ofvertebra 90 wherein the bore termination port 225 is oriented superiorlyto direct cement inflows to apply forces against cancellous bone 122 andthe superior cortical endplate 248 of the vertebra. A method ofdelivering bone cement comprises providing a flow source 250 (thepressure source 150 and cement source 145, in combination, areidentified as flow source 250 in FIG. 13) for bone cement inflows and acontroller 125B for control of the bone cement inflows, and inflowingthe bone cement into a vertebral body wherein the controller 125Badjusts an inflow parameter in response to a measured characteristic ofthe cement. In one embodiment, the measured characteristic istemperature of the bone cement measured by thermocouple 235 in theworking end 115A. The controller 125B can be any custom computerizedcontroller. In one embodiment, the system can utilize a commerciallyavailable controller manufactured by EFD Inc., East Providence, R.I.02914, USA for flow control, wherein either a positive displacementdispensing system or an air-powered dispensing system can be coupled tothe flow source 250. In response to feedback from thermocouple 235 thatis received by the controller 125B, any inflow parameter of the bonecement flow can be adjusted, for example cement injection pressure, theinflow rate or velocity of the bone cement flows or the acceleration ofa bone cement flow. The controller 125B also can preferably vary anyinflow parameter with time, for example, in pulsing cement inflows tothereby reduce a vertebral fracture, or move cancellous or cortical bone(see FIGS. 14A-14B). The cement 120 can be introduced in suitablevolumes and geometries to treat fractures or to prophylactically treat avertebra.

In another method corresponding to the invention, the flow source 250,controller 125B and Rf energy source 125A are provided as shown in FIG.13. The controller 125B again is capable of adjusting any bone cementdelivery parameter in response to impedance and/or temperature. Thecontroller 125B adjusts at least one cement delivery parameter selectedfrom cement volume, pressure, velocity and acceleration of the inflowingcement. The controller 125B also can vary pressure of the inflowingcement or pulse the cement inflows. In this embodiment, the controller125B also is capable of adjusting energy delivered from Rf energy source125A to the inflowing cement 120 in response to impedance, temperature,cement viscosity feedback or cement flow parameters to alter cementviscosity as described above. Cement viscosity can be calculated by thecontroller 125B from temperature and pressure signals. The controller125B also is capable of being programmed with algorithms to ramp-up andramp down power in one or more steps, or can be programmed to pulsepower delivery to the bone cement 120 (FIGS. 14A-14BA).

As can be seen in FIGS. 14B and 14C, the inflowing cement 120 can bedirected to apply forces against cancellous bone 122 and the superiorcortical endplate 248 of the vertebra, or the working end can be rotatedto introduce cement 120 and apply forces in other directions. In thisembodiment, the extension of the working end 115A in cancellous boneserves as a support for causing expansion pressures to be directedsubstantially in the direction of cement flows. The method of treatingthe vertebra includes translating (by helical advancement) and rotatingthe introducer 110A to thereby alter the direction of cementintroduction. In another embodiment (not shown), the introducer 110A cancomprise an assembly of first and second concentric sleeves wherein theouter sleeve has threads 220 for locking the assembly in bone and theinner sleeve is rotatable to adjust the angular direction of port 225wherein the sleeves are locked together axially. This embodiment can beused to intermittently angularly adjust the direction of cement outflowswhile helical movement of the outer sleeve adjusts the axial location ofport 225 and the cement outflows.

In another method of the invention, referring back to FIG. 14A, theaspiration introducer sleeve 242 can be inserted into the vertebral body90, for example through the opposing pedicle. The controller 125B can beprogrammed to alter aspiration parameters in coordination with any bonecement inflow parameter. For example, the cement inflows can be pulsedand the aspiration forces can be pulsed cooperatively to extract fluidsand potentially embolic materials, with the pulses synchronized. In onemethod, the cement inflows are pulsed at frequency ranging between about1 per second and 500 per second with an intense, high acceleration pulsewhich causes bone marrow, fat, blood and similar materials to becomesusceptible to movement while at the same time the aspiration pulses arestrong to extract some mobile marrow etc into the aspiration sleeve 242.In FIG. 14A, the aspiration sleeve 242 is shown with single port in itdistal end. It should be appreciated that an aspiration sleeve 242 thathas a plurality of inflow ports along the length of the sleeve, a sleevethat is curved or can be of a shape memory alloy (e.g., Nitinol) forintroduction in a curved path in the anterior of posterior region of avertebral body as indicated by lines 260 and 260′ in FIG. 14A, can alsobe used. In another embodiment, the aspiration sleeve can extend throughthe introducer 110A or can comprise an outer concentric sleeve aroundthe introducer 110A.

FIGS. 15A and 15B illustrates another embodiment of a method fordelivering bone fill material wherein the controller 125B and pressuresource 150 are configured to introduce a flowable cement into theinterior of a vertebra under widely varying velocities and rates ofacceleration to optionally (i) provide first slow flow rates to allowcement flow and interdigitation into and through cancellous bone, and(ii) provide second higher flow rates that disallow cementinterdigitation and flow into and through cancellous bone. At suitablehigh acceleration and flow velocity, for example in a pulse of cementflow into bone, the accelerated flow apply forces to bone substantiallyacross the surface of the cement plume which can displace cancellousbone rather than allowing the cement to flow into the cancellous bone.

FIG. 15A illustrates the system of FIG. 13 in a method of use whereinthe controller 125B and pressure source 150 are actuated to cause avolume of cement 120 to flow into cancellous bone 122 under a suitablelow pressure to allow the cement to interdigitate with, and flow into,the cancellous bone. The flow of cement depicted in FIG. 15A can beaccompanied by the application of aspiration forces as described above.

FIG. 15B illustrates another aspect of the method wherein the controller125B and pressure source 150 are actuated to flow cement with a highacceleration rate and velocity that disallows the cement from havingtime to flow into pores of the cancellous bone. The acceleration andvelocity are selected to disallow cement interdigitation, which therebycauses the application of force to bone across the surface of the cementplume 265 (FIG. 15B). The application of such forces across the surfaceof cement plume 265 is further enabled by providing a suitable highviscosity cement as described above, which includes selectivelyincreasing cement viscosity by means of energy delivery thereto. Themethod of the invention can include one or more sequences of flowingcement into the bone to first cause cement interdigitation (FIG. 15A)and then to apply expansion forces to the bone by at least one highacceleration flow (FIG. 15B). Of particular interest, the method ofusing high acceleration flows, for example in pulses, causes the cementvolume to apply forces to bone akin to the manner is which a mechanicalexpander or balloon expander would apply forces to bone. That is,expansion forces are applied across the entire surface of cement plume265 similar to the manner in which mechanical instruments applyexpanding forces across the bone engaging surface of the instrument. Themethods are adapted for reducing a vertebral fracture and forselectively applying forces to move cancellous bone and cortical bone.

Retrograde Sensing Systems and Methods

FIG. 16 illustrates another embodiment of an introducer 110A for safeintroduction of bone cements into a vertebra that incorporates a sensingsystem 280. The sensing system 280 includes the introducer or cannula110A with at least one distal port 225 for injection of bone cement intoa vertebra 90, as described previously with respect to FIGS. 13-15B.This sensing system 280 further includes at least one electrode carriedabout an otherwise insulative exterior surface 278 of the cannula orintroducer 110A. In the illustrated embodiment, the sensing system 280has three electrodes or sensors 280 a, 280 b, 280 c disposed about asurface of the introducer 110A, but it can be appreciated that more orfewer such electrodes can be used. In the illustrated embodiment, theelectrodes 280 a, 280 b, 280 c are ring electrodes, however otherconfigurations are possible. Preferably, the electrodes 280 a, 280 b,280 c are independently coupled to a low voltage power source 285, whichcan be a DC or AC source, and to a controller 286 that allows formeasurement of impedance between a pair of the electrodes 280 a, 280 b,280 c or between the electrodes 280 a, 280 b, 280 c and anotherelectrode 288 (in phantom) located in a more proximal location on theintroducer 110A that contacts tissue, or between electrodes 280 a, 280b, 280 c and a ground pad. Such impedance measurements canadvantageously provide the physician with instant feedback thatindicates whether there in a flow 290 of bone cement 120 along thecannula 110A (e.g., a retrograde flow). Retrograde flows of cement canbe seen by imaging means, but imaging is typically not performedcontinuously during vertebroplasty. Further, the cannula itself mayobscure clear imaging of a cement flow. Such retrograde cement flows, ifunnoticed, could leak through a fracture to contact nerves and/or thespinal cord. Though the sensors 280 a, 280 b, 280 c in the illustratedembodiment are adapted to measure impedance, the sensors 280 a, 280 b,280 c can be adapted to measure other suitable electrical, chemical ormechanical parameters, such as temperature, voltage, and reflectance.

In FIG. 16, it can be seen that the retrograde flow 290 of bone cement120 along the cannula 110A passes by, and in one embodiment may contact,first and second electrodes 280 a and 280 b, which will alter theimpedance (or other sensed parameter) measured between the first andsecond electrodes 280 a, 280 b from the normal tissue impedance. Thecontrol algorithms advantageously create a signal to notify thephysician of the variation in impedance measurement. The signal can be atone, a visual signal such as a light and or a tactile signal such as avibrator in the handle of the introducer 110A. The controller 286 canpreferably switch sensing between various electrodes (e.g., adjacentelectrodes or non-adjacent electrodes) to indicate the location of anymigrating cement. The cement delivery system may use a conductive bonecement, as described in U.S. application Ser. No. 11/209,035 filed Aug.22, 2005, which will have a significantly different impedance thantissue to allow for easy detection of cement flows. It should beappreciated that any conventional bone cement will have a differentimpedance than bone tissue so that a retrograde flow 290 of conventionalbone cement can be detected. The controller 286 algorithms can beconfigured for any type of bone cement, wherein each type has a knownimpedance, reflectance, etc. For example, a bone cement formula can beprovided for use with the controller 286 to measure impedance and detectvariations in impedance due to bone cement flow. In one embodiment, thecontroller 286 preferably compares the sensed parameter (e.g.,impedance) of the retrograde flow bone cement with a known value orvalue range for said parameter in bone tissue (e.g., vertebral tissue).The known values for the parameter can be stored in an algorithm orformulas stored in the controller 286 or in a separate memory. Inanother embodiment, the controller 286 can measure impedance (or otherparameter values) of vertebral tissue adjacent at least one of theelectrodes 280 a, 280 b and compare said measured impedance to ameasured impedance of retrograde bone cement flow adjacent another ofthe electrodes 280 a, 280 b.

In another embodiment, the feedback from the sensing system 280 of FIG.16 can be further adapted for actuating a control mechanism relating tooperation of the vertebroplasty system. In one embodiment, as describedin FIGS. 13-15B, the flow of bone cement is controlled by a controller125B and pressure source 150. Feedback from the sensors 280 a, 280 b,280 c to the controller 286, which are used to measure impedance, can beused to adjust or terminate the flow of bone cement from the pressurizedsource of bone cement 145.

In another embodiment, the feedback from the sensing system 280 of FIG.16 can be adapted to expand an expansion structure 295 (in phantom)about the surface of the cannula to prevent further bone cementmigration. The expansion structure can be a fluid filled balloon, athermally expandable polymer that has resistive or Rf energy appliedthereto, or an elastomeric structure that can be expanded by axially orrotationally moving concentric cannula sleeves.

In another embodiment, the sensing system 280 can include a thermocouple282 for measuring temperature of media proximate the exterior surface278 of the cannula 110A. Such a temperature sensor can be well insulatedfrom the interior bore of the cannula which will carry exothermiccement. The sensor system 280 can also include a light sensor systemthat can measure and compare a tissue parameter and a bone cementparameter. For example, a fiber optic can be provided to emit and/orreceive light at the electrode locations in FIG. 16. Various parametersare possible such as reflectance. Alternatively, the bone cement can beconfigured with signaling compositions to cooperate with light emittedfrom a light source.

While the sensing system 280 has been described with the sensors beingproximal to the cement injection port 225 of the cannula 110A, thesensors also can be elsewhere along the cannula 110A, for example at thedistal end of the cannula 110A, to detect cement flow in that direction,such as in an anterograde direction.

FIG. 17, shows another embodiment of a bone fill introducer or injectorsystem 310A for treatment of the spine, such as in a vertebroplastyprocedure. Introducer system 310A is used for placement a fill materialfrom source 145, wherein injection of the fill material is carried outby the pressure mechanism or source 150. The pressure mechanism 150 canbe a manually operated syringe loaded with bone fill material, or anon-manual pressurized source of fill material. The source 145 of fillmaterial preferably includes a coupling or fitting 314 for sealablelocking to a corresponding fitting 315 at a proximal end 316 of anelongated introducer sleeve or cannula 320. In one embodiment, thesource of fill material 145 is coupled directly to fitting 315 with athreaded coupling, a Luer lock or the like. In another embodiment as inFIG. 17, a flexible tube 318 (phantom view) is used to couple the source145 to the introducer 320.

With continued reference to FIG. 17, the bone fill introducer system310A includes the elongated sleeve 320 with interior channel 322extending along axis 324, wherein the channel 322 terminates in anoutlet opening 325. In the illustrated embodiment, the outlet opening325 is disposed proximal the distal end of the elongated sleeve 320 andfaces a side of the sleeve 320. In the illustrated embodiment, theoutlet opening 325 is a single opening. In other embodiments, aplurality of outlet openings can be disposed on an outward surface 328of the sleeve 320 about a circumference of the sleeve 320. In anotherembodiment, an outlet opening can be provided at the distal tip 330. Inone embodiment, the distal tip 330 is blunt. In another embodiment, thedistal tip can be sharp as with a chisel-like tip.

As can be seen in FIG. 17, the exterior surface 328 of the introducersleeve 320 carries at least one sensor system 344 adapted to sense theflow or movement of a fill material 345 (see FIGS. 18A-18C) proximate tothe sensor system 344. The introducer sleeve 320 and sensor system 344are particularly useful in monitoring and preventing extravasion of afill material 345 in a vertebroplasty procedure. In the illustratedembodiment, the sensor system 344 comprises a plurality of spaced apartelectrodes or sensors 354 a, 354 b, 354 c coupled to the electricalsource 125A via an electrical connector 356 preferably disposed at theproximal end of the introducer 320. The electrodes 354 a, 354 b, 354 care preferably spaced apart about the circumference of the introducer320, as well as axially along the length of the introducer 320. Theelectrical source 125A preferably carries a low voltage direct current,such as an Rf current, between the opposing potentials of spaced apartelectrodes. The voltage is preferably between about 0.1 volts to about500 volts, or from between about 1 volt to about 5 volts, and preferablycreates a current path through the tissue between a pair of electrodes.The current can be continuous, intermittent and/or multiplexed betweendifferent electrode pairs or groups of electrodes.

In one embodiment and method of use, referring to FIGS. 18A-18C, theintroducer sleeve 320, as shown in FIG. 17, is used in a conventionalvertebroplasty procedure with a single pedicular access through avertebra 350. Alternatively, a bi-pedicular access can be used. The fillmaterial 345 is preferably a bone cement, such as PMMA, that is injectedinto cancellous bone 346 within the interior of a cortical bone surface348 of the vertebra 350.

FIGS. 18A-18B show a progressive flow of cement 345 that exits theintroducer sleeve 320 through outlet 325 and into the interior of thevertebra 350. FIG. 18C depicts a situation that is known to occur wherebone is fractured along the entry path of the introducer 320, or wherethe pressurized cement finds the path of least resistance to beretrograde along the surface of introducer 320. The retrograde flow ofcement, as in FIG. 18C, if allowed to continue, could lead to cementextravasion into the spinal canal 352. In one embodiment, the sensorsystem 344 is actuated when the bone cement 345 comes into contact withat least one of the sensors 354 a, 354 b, 354 c of the sensor system344. In another embodiment, the sensor system 344 continually monitorsthe impedance adjacent the sensors 354 a, 354 b, 354 c of the sensorsystem 344.

The arrangement of electrodes 354 a, 354 b, 354 c can be spaced apartangularly and axially as shown in FIG. 17, or the electrodes can be ringelectrodes (see FIG. 16), helically spaced electrodes, or the electrodescan be miniaturized electrodes as in thermocouples, MEMS devices or anycombination thereof. The number of sensors or electrodes can range fromabout 1 to 100 and can be adapted to cooperate with a ground pad (e.g.,ground pad 170 in FIG. 13) or other surface portion of sleeve 320. Inone embodiment, the electrodes can include a PTC or NTC material(positive temperature coefficient of resistance or negative temperaturecoefficient of resistance) to thereby function as a thermistor to allowmeasurement of temperature, as well as functioning as a sensor. Thesensor system 344 includes the controller 125B, which measures at leastone selected parameter of the current flow to determine a change in aparameter such as impedance. When the bone cement 345 (e.g., anon-conductive bone cement material) contacts one or more electrodes ofthe sensor system 344, the controller 125B identifies a change in theselected electrical parameter and generates a signal to the operator. Inanother embodiment, the controller 125B identifies a change in theselected parameter when the bone cement 345 passes proximal one or moreof the sensors of the sensor system 344 and communicates a signal to theoperator corresponding to said change in said selected parameter. Saidselected parameter can be at least one electrical property, reflectance,fluorescence, magnetic property, chemical property, mechanical propertyor a combination thereof.

Now referring to FIG. 19, another embodiment of a bone fill system 310Bfor vertebroplasty procedures is shown. The bone fill system 310Bincludes an introducer 320 with a proximal portion 360 a that is largerin cross-section than a distal portion 360 b thereof. Thisadvantageously allows for lower injection pressures since the cementflow needs to travel a shorter distance through the smallest diameterdistal portion 360 b of the introducer 320. In one embodiment, thedistal portion 360 b of the introducer 385 can have a cross sectionranging between about 2 mm and 4 mm with a length ranging between about40 mm and 60 mm. Similarly, in one embodiment the proximal portion 360 aof the introducer 320 can have a cross section ranging between about 5mm and 15 mm, or between about 6 mm and 12 mm. However the proximal anddistal portions 360 a, 360 b of the introducer 320 can have othersuitable dimensions.

With continued reference to FIG. 19, the bone fill system 310B alsoincludes a sensing system 365 for detecting a retrograde flow of bonecement along an outer surface 366 of the introducer 320. In theillustrated embodiment, the sensing system 365 includes a first and asecond electrode 365 a, 365 b in the form of spaced apart exposed flatwire surfaces that are disposed on the surface 366 of the distalintroducer portion 360 b, wherein the introducer 320 includes a surfaceinsulator layer 368. In one embodiment, the insulator layer 368 coversthe entire surface of the distal introducer portion 360 b, and morepreferably the entire surface of the introducer 320, except where theelectrodes 365 a, 365 b are disposed. In another embodiment, the distalintroducer portion 360 b can be a conductive metal introducer portionwith a first polarity electrode that is exposed in cut-out portions ofinsulator layer 368 and another opposing polarity electrode is disposedon the surface of the insulator layer 368. In the illustrated embodimentthe electrodes or sensors 365 a, 365 b have a helical shape and extendhelically along the introducer 320. However, in another embodiment, theelectrodes 365 a, 365 b can have other suitable shapes (e.g., ringelectrodes). Though FIG. 19 shows two electrodes 365 a, 365 b, one ofordinary skill in the art will recognize that more or less than twoelectrodes can be provided.

In the illustrated embodiment, the electrodes 365 a, 365 b arepreferably electrically connected to the energy source 125A andcontroller 125B via lead lines (dashed lines). In one embodiment, theenergy source 125A is an Rf electrical source capable of deliveringsufficient Rf energy (i) to coagulate tissue which in turn willpolymerize adjacent bone cement to create a dam to inhibit retrogradeflows, or (ii) to deliver energy to a conductive bone cement 345 toinhibit retrograde flows. The opposing polarity electrodes indicated bythe (+) and (−) can be spaced apart any selected distance to thusoperate in a bi-polar manner wherein the depth of tissue coagulationwill depend, at least in part, on the approximate center-to-center oredge-to-edge dimensions of the positive and negative electrodes. Thus,any such electrode arrangement can be adapted to both sense retrogradeflows and thereafter deliver energy to such flow in response to at leastone feedback algorithm in the controller 125B. Any suitable type ofexternal thermal energy emitter that is linked to the sensor system 365for inhibiting retrograde flows can be used, such as the energy emitter128 discussed above with respect to FIG. 2A. The exterior thermal energyemitter can be a resistively heated emitter, a resistive coil, a PTCheating element, a light energy emitter, an inductive heating emitter,an ultrasound source, a microwave emitter or any other electromagneticenergy emitter or Rf emitter that cooperates with the bone cement.

FIG. 20 shows another embodiment of an introducer system 500 thatincludes a thin wall sleeve or sheath 510 removably slidable over aninjector or introducer 520 (in phantom) used in conventionalvertebroplasty procedures and adapted for ejection of bone fill material(e.g., bone cement) through an outlet opening 522 (in phantom) at adistal end of the introducer 520. In the illustrated embodiment, thesheath 510 has an opening 515 formed at a distal end 518 of the sheath510, wherein the opening 515 preferably aligns with the opening 522 ofthe of the introducer 520 when the sleeve 510 is deployed over theintroducer 520. In the illustrated embodiment, the sleeve 510 ispreferably a thin-wall flexible sleeve. For example, the sleeve 510 canbe fabricated of silicone, polyethylene, urethane, polystyrene, or anyother suitable polymer. The sleeve 510 can be elastic and dimensionedfor a substantially tight grip fit about the injector 520. In anotherembodiment, the sleeve 510 can include a tacky or adhesive surface forengaging the injector 520. In another embodiment, the sleeve 510 can beinvertable with or without a self-stick surface to roll over theinjector 520 (e.g., as a condom). In another embodiment, the sleeve 510can comprise a heat shrink material to shrink over the injector 520. Inanother embodiment, the sleeve 510 can be a thin-wall flexible sleevethat has a large diameter compared to injector 520 so that the sleeve510 fits loosely over the injector 520, where the sleeve 510 is adaptedto longitudinally fold about the injector 520 for inserting into a pathin the cancellous bone. Upon any retrograde flow of cement, said thinwall material advantageously tends to crumple and engage the cancellousbone to form a mechanical dam to inhibit retrograde flows. In stillanother embodiment (not shown), the sleeve can be a thin-wallsubstantially rigid or rigid sleeve that can slip over the introducer520, and be made of, for example, metal or a hard plastic.

The system 500 preferably includes a sensor system 560, which includes afirst and second spaced apart electrodes 565 a, 565 b, similar to theelectrodes 365 a, 365 b described above with respect to FIG. 19. Theelectrodes 565 a, 565 b are preferably disposed on an outer surface 512of the sleeve 510. In the illustrated embodiment, the electrodes orsensors 565 a, 565 b have a helical shape and extend helically along thelength of the sleeve 510. However, the electrodes 565 a, 565 b can haveany suitable shape (e.g., ring electrodes). Additionally, any number ofelectrodes 565 a, 565 b can be provided.

With continued reference to FIG. 20, the sensor system 560 includes anelectrical connector 570 that connects to a proximal end 514 of thesleeve 510. The connector 570 is configured for detachable coupling withelectrical leads 572A, 572B that extend to the electrical or energysource 125 a. The electrical leads 572A, 572B preferably areelectrically connected to the electrodes 565 a, 565 b. In oneembodiment, the electrodes 565 a, 565 b can be used to sense aretrograde flow of bone cement, where the signals (e.g., of impedance asdiscussed above) are communicated to the controller 125B, which in turngenerates a signal (e.g., visual, tactile, auditory) to notify theoperator of the retrograde flow, as discussed above. In anotherembodiment, the sensor system 560 can operate as an energy-deliverysystem, where the controller 125B controls the operation of the energysource 125A to control the delivery of electricity to the electrodes 565a, 565 b to, for example, polymerize bone cement proximal the sensors565 a, 565 b or coagulate tissue proximal the sensors 565 a, 565 b, asdiscussed above.

Hydraulic Pressure Mechanism

Returning to FIG. 19, system 310B includes a container of fill materialor source 145′ that is pressurized by a pressure mechanism 150′. Thepressure mechanism 150′ can be a hydraulic source. For example, in oneembodiment, the hydraulic source can include a syringe, or plurality ofsyringes, with a conduit containing a working fluid therein andconnecting the syringe to a proximal end of the fill material source145′. The working fluid can transfer the force generated by the syringeonto a piston 358 (e.g., a floating piston) that travels through asleeve 145A of the fill material source 145′ to eject fill material fromthe fill material source 145′ into the introducer 320. In anotherembodiment the hydraulic source can comprise a plurality of syringesconnected via conduits having working fluids therein, the forcegenerated by one syringe transferred through the working fluid onto apiston of a downstream syringe, and eventually transferred to the piston358 in the sleeve 145A. In still another embodiment, the hydraulicmechanism can include a screw pump actuatable to transmit a force onto aworking fluid in a conduit, which in turn transmits said force onto thepiston 358 in the sleeve 145A. However, the pressure mechanism 150′ cancomprise other suitable mechanisms.

Temperature Control Systems

FIG. 21, shows another embodiment of a bone fill delivery system 310C.The system 310C is similar to the system 310B in FIG. 19, except asnoted below. Thus, the reference numerals used to designate the variouscomponents of the system 310C are identical to those used foridentifying the corresponding components of the system 310B, except asnoted below.

The system 310C can include a sensing system for detecting retrogradeflows of bone cement, as discussed above. Further, the system 310Cpreferably includes a cooling system or mechanism 380, which is shownschematically in FIG. 21. In one embodiment, the cooling mechanism 380is carried within the container 145 that carries the fill material(e.g., PMMA bone cement or similar in-situ hardening cement) as shown inFIG. 22. In another embodiment, the cooling mechanism 380 can bedisposed about the container 145. As can be seen in FIG. 21, theelectrical source 125A and controller 125B are coupled to the introducer320 via leads that are electrically connected to a detachable coupling382 coupleable to the introducer 320. A stylet 384 is also provided,preferably having a sharp tip, for use in embodiments where theintroducer 320 has a distal open port 325′.

The cooling system 380 of FIG. 21 advantageously maintains a volume ofmixed bone cement at a pre-determined temperature to inhibitacceleration of the exothermic heating thereof, thus extending theworking time of the cement. In one embodiment, as shown in FIG. 21, theintroducer 320 is an independent introducer 320 sized and configured forintroducing the bone cement 345 (FIGS. 18A-18C) into the vertebra 350.In the illustrated embodiment, the bone cement container 145 has afitting and optional flexible sleeve connector 388 for providing asubstantially sealed and substantially pressure-tight coupling betweenthe container 145 and the introducer 320 The connector 388 preferablyhas a length of between about 10 mm and about 100 mm and can optionallyinclude a cooling system disposed therein.

The cooling system 380 preferably includes at least one of an activecooling system and a passive cooling system. In one embodiment, shown inFIG. 21, the cooling system 380 includes a thermoelectric system with atleast one element 390 (e.g., a Peltier element) in contact with athermally conductive wall portion 392 of the container 145. In anotherembodiment, the cooling system 380 includes a chilled fluid circulationsystem with channels 394 disposed proximate the wall portion 392 ofcontainer 145 (See FIG. 22). In another embodiment (not shown) thecooling system 380 includes a freon system with an expansion channelinside the wall portion 392 of the container 145. However, the coolingsystem 380 can include other suitable active cooling arrangements. Instill another embodiment (not shown), the cooling system 380 includes aheat pipe system with at least one elongate channel or concentricchannel in the wall portion 392 of the container 145, which wicks heataway from the container 145 to a heat exchanger component. In yetanother embodiment (not shown), the cooling system 380 is a passivesystem that includes an open cell graphite structure for conducting heataway from the container 145 to a heat exchanger component. In oneembodiment, the open cell graphite is PocoFoam™ manufactured by PocoGraphite, Inc. 300 Old Greenwood Road, Decatur, Tex. 76234.

With continued reference to FIG. 21, the bone fill injection system 310Cincludes the pressure source or mechanism 150′, as discussed above withrespect to FIG. 19. In the illustrated embodiment, the pressure source150′ is a hydraulic mechanism coupled to the container 145 via flexibleor deformable tubing 396 to drive the piston 358.

As shown in FIG. 21, the controller 125B can be further coupled to atleast one sensing system 440 for determining the viscosity of the bonecement in the container 145. Preferably, the sensing system 440 is atleast partially disposed in the container 145. The controller 125Bpreferably includes algorithms for preventing any flow of bone cementthrough the introducer 320 until the cement has reached a pre-determinedviscosity.

In one embodiment, the sensing system 440 includes an electricalparameter sensing system for querying an electrical parameter of apolymerizable bone cement to thereby determine its viscosity. Such anelectrical sensor can preferably measure at least one of capacitance,conductivity and impedance. Another embodiment of sensing system 440includes a mechanical parameter sensing system for measuring amechanical parameter of the bone cement. For example, the mechanicalparameter sensing system can query the bone cement by applying anacoustic wave thereto. In still another embodiment, the sensing system440 includes an optical parameter sensing system for determining theviscosity of the bone cement by measuring an optical parameter of apolymerizing bone cement. For example, the optical parameter sensingsystem can measure reflectance of the bone cement. In anotherembodiment, the optical parameter sensing system can acquire an opticalsignature of a bone cement that carries a thermochromic composition. Inanother embodiment, the sensing system 440 includes a temperaturesensing system for determining the viscosity of the bone cement via ameasured the temperature of a polymerizable bone cement in the container145. In still another embodiment, the sensing system 440 includes astrain gauge (not shown) disposed in the container 145 or drive systemto determine the viscosity of the cement. In another embodiment, thesensing system 440 uses a pressure sensor, such as a MEMS pressuresensor, to determine the viscosity of the bone cement. Any of thesensing systems described herein can be configured to query theparameter of the bone cement continuously or intermittently at anysuitable rate.

With continued reference to FIG. 21, the bone fill injection system 310Coptionally further includes a thermal energy emitter 420 (See FIG. 23A)disposed within an interior channel 424 of the introducer 320 forheating a flow of bone cement exiting the introducer 320 through theoutlet opening 325, as shown in FIG. 23A. In one embodiment, the thermalenergy emitter 420 is an Rf emitter adapted for heating a conductivebone cement as disclosed in the following co-pending U.S. patentapplications: applications Ser. No. 11/165,652 filed Jun. 24, 2005;application Ser. No. 11/165,651 filed Jun. 24, 2005, now U.S. Pub. No.2006-0122622; application Ser. No. 11/196,045 filed Aug. 2, 2005;application Ser. No. 11/208,448 filed Aug. 20, 2005; and applicationSer. No. 11/209,035 filed Aug. 22, 2005, the entire contents of whichare hereby incorporated by reference and should be considered a part ofthis specification. In another embodiment, the thermal energy emitter420 delivers thermal energy to the bone cement via conduction in thedistal region of the introducer 320. The thermal energy emitter 420 canbe a resistive heat emitter, a light energy emitter, an inductiveheating emitter, an ultrasound source, a microwave emitter and any otherelectromagnetic energy emitter to cooperate with the bone cement.

In another embodiment, shown in FIG. 23B, the thermal energy emitter isa resistive heater 420′ with a resistive heating element 422. Theheating element 422 preferably has a helical configuration, though othersuitable configurations are possible, such as an axial configuration.Additionally, the heating element 422 is preferably disposed in aninterior bore 424 of the introducer 320 and can optionally be formedfrom (or coated with) a positive temperature coefficient material andcoupled to a suitable voltage source to provide a constant temperatureheater as is known in the art. Preferably, the heating element 422 iscarried within an insulative coating 426 on an interior surface of theintroducer 320.

In one embodiment, the thermal energy emitter 420, 420′ raises thetemperature of the chilled bone cement to body temperature or withinabout 5° C. above or below body temperature. In another embodiment,thermal energy emitter 420, 420′ raises the temperature of the chilledbone cement 345 to at least about 45° C., at least about 55° C. inanother embodiment, at least about 65° C. in still another embodiment,and between about 45° C. and 95° C. in another embodiment to acceleratepolymerization of the bone cement 345 and increase the viscosity of aPMMA or similar bone cement. In another embodiment, the thermal energyemitter 420, 420′ raises the temperature of the chilled bone cement 345to between about 50° C. and 85° C., or between about 50° C. and 65° C.to accelerate polymerization of bone cement 345.

In the embodiments illustrated in FIGS. 21, 22 and 23A-B, the controller125B preferably controls all parameters associated with cooling of thebone cement in the container 145, cement injection pressure and/or flowrate, energy delivery to cement flows in or proximate the distal end ofthe introducer 320, sensing of retrograde flows, and energy delivery toretrograde flows about the exterior surface of the introducer 320.

FIG. 22 illustrates another system 310D for delivery of bone infillmaterial. The system 310D is similar to the system 310B in FIG. 19,except as noted below. Thus, the reference numerals used to designatethe various components of the system 310D are identical to those usedfor identifying the corresponding components of the system 310B, exceptas noted below. In the illustrated embodiment, the arrangement of theelectrodes 365 a, 365 b can be multiplexed between a bi-polar mode and amono-polar mode using a remote return electrode (ground pad) 170.

Injector Coatings

FIGS. 24 and 25 show another embodiment of a bone infill materialdelivery system 600, which again comprises a bone cement injector 620that extends to a working end 605 thereof. However, the featuresdescribed below are applicable to any electrosurgical probe or otherheated probe. The injector 620 has a handle portion 640 and an extensionportion 642 with a flow passageway 424 extending therethrough (See FIG.25). The extension portion 642 is preferably sized and shaped for use ina vertebroplasty procedure.

As shown in FIG. 24, the injector 620 has an exterior surface thatincludes a coating 625. The coating 625 preferably comprises a thinlayer of a non-metallic material, such as an insulative amorphousdiamond-like carbon (DLC) or a diamond-like nanocomposite (DCN). Suchcoatings advantageously inhibit scratching (e.g., have high scratchresistance), as well as have lubricious and non-stick characteristicsthat are useful in bone cement injectors configured for carryingelectrical current for (i) impedance sensing purposes; (ii) for energydelivery to bone fill material; and/or (iii) ohmic heating of tissue,such as the injectors 110A, 320, 620 discussed herein. In a preferredembodiment, the coating has a scratch resistance of at least about 10 onthe Mohs scale, or above about 12 on the Mohs scale in anotherembodiment, or above about 14 on the Mohs scale in still anotherembodiment. A surface of the injector can have a lubricious levelrepresented by a static coefficient of friction of less than about 0.5in one embodiment, less than about 0.2 in another embodiment, and lessthan about 0.1 in still another embodiment. In one embodiment, the DLCor DNC coatings can have an overlying layer of Teflon, or similarmaterial, to provide the desired lubricious level. For example, wheninserting a bone cement injector through the cortical bone surface of apedicle and then into the interior of a vertebra, it is important thatthe exterior insulative coating portions do not fracture, chip orscratch to thereby ensure that the electrical current carrying functionsof the injector 110A, 320, 620 are not compromised.

With continued reference to FIG. 24, the source of bone fill material145 is coupleable to the flow passageway 424 of the introducer 620. Inaddition, the handle portion 640 of the injector 620 includes aconnector 645A that allows for releasable connection of the injector 620with an electrical connector 645B coupled to the electrical or energysource. The extension portion 642 is preferably sized and shaped for usein a vertebroplasty procedure and to the controller 125B via anelectrical cable 650. The electrical cable 650 preferably carriescurrent to the working end 605 of the bone cement injector 620. Inanother embodiment, the electrical cable 650 can be integrated into andpermanently attached to the handle portion 640 of the injector 620.

As shown in FIG. 24, the system 600 includes a sensor system 660 thatincludes a series of electrodes 662 at the working end 605 of theintroducer 620. In the illustrated embodiment, the electrodes 662 arering-like electrodes, though other suitable configurations can be used(e.g., helical shaped electrodes). Though FIG. 24 shows five electrodes662, the sensor system 660 can have more or fewer electrodes. In theillustrated embodiment, the electrodes 662 are defined bycircumferential rings of exposed surfaces of a metal cannula, where theamorphous diamond-like carbon coating has been removed, for example, byetching. In use, the low voltage current provide by the electricalsource 125A is coupled to the ring-like electrodes 662 from a secondopposing polarity electrode in the working end 605 (or a remoteelectrode such as a ground pad). As bone cement covers the ring-likeelectrodes 660, impedance will change to thus allow a signal ofretrograde bone cement migration, as described above, to be generatedand communicated by the controller 125B to the operator. In oneembodiment, the electrical source 125A provides energy to the electrodes662 for sensing a retrograde flow. In another embodiment, the electricalsource 125B provides energy to the electrodes 662 for heating of bonecement (e.g., polymerization of bone cement0 or tissue.

FIG. 25 shows a schematic partial cross-sectional view of the introducer620. The introducer 620 in FIG. 25 is similar to the introducer 320 inFIG. 23B, except as noted below. Thus, the reference numerals used todesignate the various features of the introducer 620 are identical tothose used for identifying the corresponding features of the introducer320, except as noted below. In the illustrated embodiment, theintroducer 620 includes the thermal energy embitter 420′, which includesthe resistive heating element 422, coupled to the electrical source 125Aand controller 125B. The source of fill material 145 provides a flow ofbone infill material (e.g., bone cement) through the flow passageway424, which extends through the introducer 620 to the outlet opening 325.As discussed above, the introducer 620 has the coating 625 disposed overan outer surface thereof. As shown in FIG. 25, the introducer 620 alsohas an amorphous diamond-like carbon (DLC) or a diamond-likenanocomposite (DCN) coating 630 within the interior passageway 424 ofthe bone cement injector 620, though the injector can be of any typedescribed above.

Suitable amorphous diamond-like carbon coatings and diamond-likenanocomposites are available from Bekaert Progressive CompositesCorporations, 2455 Ash Street, Vista, Calif. 92081 or its parent companyor affiliates. Further information on said coatings can be found at:http://www.bekaert.com/bac/Products/Diamond-like %20coatings.htm, thecontents of which are incorporated herein by reference. The diamond-likecoatings preferably comprise amorphous carbon-based coatings with highhardness and low coefficient of friction. The amorphous carbon coatingsadvantageously exhibit non-stick characteristics and excellent wearresistance. The coatings are preferably thin, chemically inert and havea very low surface roughness. In one embodiment, the coatings have athickness ranging between about 0.001 mm and about 0.010 mm. In anotherembodiment, the coatings have a thickness ranging between about 0.002 mmand about 0.005 mm. The diamond-like carbon coatings are preferably acomposite of sp2 and sp3 bonded carbon atoms with a hydrogenconcentration of between about 0% and about 80%. Another suitablediamond-like nanocomposite coating (a-C:H/a-Si:O; DLN) is made byBakaert and is suitable for use in the bone cement injector describedabove. The materials and coatings are known by the names Dylyn®Plus,Dylyn®/DLC and Cavidur®.

In another embodiment, the metal-doped amorphous diamond-like carbon ordiamond-like nanocomposite can be used in an electrosurgical surface ofa blade, needle, probe, jaw surface, catheter working end and the like.In one embodiment, the surface of a probe or jaw can comprise a patternof metal-doped amorphous diamond-like carbon portions and adjacent orsurrounding insulative amorphous diamond-like carbon portions.

In another embodiment, the amorphous diamond-like carbon or diamond-likenanocomposite can be used in a high temperature circuit board. Such acircuit board can comprise any insulative substrate together with anelectrical circuit deposited thereon, wherein the circuit is of ametal-doped amorphous carbon or diamond-like nanocomposite. The circuitboard can use depositions of the DLC or DLN that have a thicknessranging between about 1 micron and 10 microns. The width of theelectrical circuit paths have a width of less than about 1000 microns;100 microns; 10 microns and 1 micron.

In one embodiment, the electrodes 280 a, 280 b, 280 c, 344, 365, 662 donot come in contact with adjacent tissue due to, for example, thepresence of a coating on an external surface of the injector 110A, 320,620, such as coating 625. Accordingly, the electrodes 280 a, 280 b, 280c, 344, 365, 662 can preferably sense a retrograde flow without being indirect contact with bone cement or tissue, and can direct energy to saidbone cement or tissue without being in direct contact with the same to,for example, coagulate tissue or polymerize bone cement.

In another embodiment, energy can be delivered via the electrodes 280 a,280 b, 280 c, 344, 365, 662 of the systems described above to heatsurrounding tissue prior to introduction of bone cement into thevertebra. In another embodiment, energy can be delivered via theelectrodes 280 a, 280 b, 280 c, 344, 365, 662 of the systems describedabove to heat surrounding tissue and bone cement prior to introductionof additional bone cement into the vertebra.

The features described herein are further applicable to cure-on-demandfill materials that can be used for disc nucleus implants, wherein theconductive fill material is injected to conform to the shape of a spaceand wherein Rf current is then applied to increase the modulus of thematerial on demand to a desired level that is adapted for dynamicstabilization. Thus, the Rf conductive fill material 120, 345 can beengineered to reach a desired modulus that is less than that of ahardened fill material used for bone support. In this embodiment, thefill material is used to support a disc or portion thereof. Thecure-on-demand fill material also can be configured as an injectablematerial to repair or patch a disc annulus as when a tear or herniationoccurs

The features described herein are further applicable to cure-on-demandfill materials that can be used for plastic surgery and reconstructivesurgery wherein the conductive fill material is injected to conform to adesired shape, for example in facial plastics for chin implants, nasalimplants, check implants or breast implants and the like.

The features described herein are further applicable to cure-on-demandfill material that can be used for injection into a space betweenvertebrae for intervertebral fusion. The injection of fill material canconform to a space created between two adjacent vertebrae, or can beinjected into notches or bores in two adjacent vertebrae and theintervening space, and then cured by application of Rf current toprovide a substantially high modulus block to cause bone fusion.

In any embodiment such as for intervertebral fusion or for bone supportin VCFs, the system can further include the injection of a gas (such ascarbon dioxide) into the fill material before it is injected from a highpressure source. Thereafter, the gas can expand to form voids in thefill material as it is cured to create porosities in the hardened fillmaterial for allowing rapid bone ingrowth into the fill material.

The systems described herein can use any suitable energy source, otherthat radiofrequency energy, to accomplish the purpose of altering theviscosity of the fill material 120, 345. The method of altering fillmaterial can be at least one of a radiofrequency source, a laser source,a microwave source, a magnetic source and an ultrasound source. Each ofthese energy sources can be configured to preferentially deliver energyto a cooperating, energy sensitive filler component carried by the fillmaterial. For example, such filler can be suitable chromophores forcooperating with a light source, ferromagnetic materials for cooperatingwith magnetic inductive heating means, or fluids that thermally respondto microwave energy.

The features described herein are further applicable to additionalfiller materials, such as porous scaffold elements and materials forallowing or accelerating bone ingrowth. In any embodiment, the fillermaterial can comprise reticulated or porous elements of the typesdisclosed in co-pending U.S. patent application Ser. No. 11/146,891,filed Jun. 7, 2005, titled “Implants and Methods for Treating Bone”which is incorporated herein by reference in its entirety and should beconsidered a part of this specification. Such fillers also can carrybioactive agents. Additional fillers, or the conductive filler, also caninclude thermally insulative solid or hollow microspheres of a glass orother material for reducing heat transfer to bone from the exothermicreaction in a typical bone cement component.

Of course, the foregoing description is that of certain features,aspects and advantages of the present invention, to which variouschanges and modifications can be made without departing from the spiritand scope of the present invention. Moreover, the bone treatment systemsand methods need not feature all of the objects, advantages, featuresand aspects discussed above. Thus, for example, those skill in the artwill recognize that the invention can be embodied or carried out in amanner that achieves or optimizes one advantage or a group of advantagesas taught herein without necessarily achieving other objects oradvantages as may be taught or suggested herein. In addition, while anumber of variations of the invention have been shown and described indetail, other modifications and methods of use, which are within thescope of this invention, will be readily apparent to those of skill inthe art based upon this disclosure. It is contemplated that variouscombinations or subcombinations of these specific features and aspectsof embodiments may be made and still fall within the scope of theinvention. Accordingly, it should be understood that various featuresand aspects of the disclosed embodiments can be combined with orsubstituted for one another in order to form varying modes of thediscussed bone treatment systems and methods.

1. A bone fill material injection system, comprising: a containercarrying a bone fill material therein; an elongated introducerconfigured for introduction into a vertebral body, the introducercoupleable to the container and configured to allow a flow of the bonefill material therethrough; and a cooling mechanism coupled to thecontainer and configured to cool the bone fill material in the containerto extend a working time of the bone fill material.
 2. The system ofclaim 1, wherein the container and the introducer are coupleable to eachother so as to form a sealed pressure-tight interface therebetween. 3.The system of claim 1, wherein the cooling mechanism is disposed aboutthe container.
 4. The system of claim 1, wherein the cooling mechanismcomprises at least one of an active cooling system and a passive coolingsystem.
 5. The system of claim 4, wherein the cooling mechanismcomprises a chilled fluid circulation system.
 6. The system of claim 4,wherein the cooling mechanism comprises a thermoelectric system.
 7. Thesystem of claim 4, further comprising a pressure source coupled to thecontainer, the pressure source configured to apply a pressure to thebone fill material within the container to provide a pressurized flow ofbone fill material through the introducer.
 8. The system of claim 7,wherein the pressure source is a hydraulic source.
 9. The system ofclaim 7, further comprising a thermal energy emitter operably coupled tothe introducer, the thermal energy emitter configured to apply thermalenergy to the bone fill material to heat the bone fill material to adesired temperature.
 10. The system of claim 9, wherein the thermalenergy emitter is disposed within the introducer proximate an outletopening of the introducer, the emitter applying energy to the bone fillmaterial flowing through the introducer.
 11. The system of claim 9,wherein the thermal energy emitter is selected from the group consistingof an electromagnetic energy emitter, a radiofrequency energy emitter, alight energy emitter, a microwave emitter, a resistive heat emitter, aninductive heat emitter and an ultrasound source.
 12. The system of claim9, further comprising a controller configured to control the operationof the cooling mechanism, the thermal energy emitter and the pressuresource.
 13. The system of claim 12, further comprising a flow controlmechanism for preventing flow of the bone fill material when a viscosityof the bone fill material is less than a selected viscosity.
 14. Thesystem of claim 9, further comprising an insulative layer between thethermal energy emitter and a wall of the introducer.
 15. The system ofclaim 9, wherein the thermal energy emitter is a resistive heat emitter.16. The system of claim 15, wherein the resistive heat emitter has ahelical shape.
 17. The system of claim 15, wherein the resistive heatemitter comprises a positive temperature coefficient material configuredto provide a generally uniform temperature from the emitter.
 18. Thesystem of claim 15, further comprising an electrical source coupled tothe resistive heat emitter, the electrical source configured to providea current to the resistive heat emitter.
 19. The system of claim 9,wherein the thermal energy emitter is configured to raise a temperatureof the bone fill material flowing through a channel of the introducer toat least about 45° C., at least about 55° C. or at least about 65° C.20. A system for injecting a bone fill material, comprising: a containercarrying a bone fill material; an elongated introducer configured forintroduction into a vertebral body, the introducer coupleable to thecontainer and configured to allow a flow of bone fill materialtherethrough; and means for cooling the bone fill material within thecontainer to extend a working time of the bone fill material.
 21. Thesystem of claim 20, further comprising means for heating the bone fillmaterial to a desired temperature.
 22. A method for treating a vertebraof a human body, comprising: providing a bone fill material; cooling thebone fill material to stall the polymerization of the bone fillmaterial; heating the bone fill material to accelerate thepolymerization of the bone fill material; and delivering the bone fillmaterial into a vertebral body.
 23. The method of claim 22, whereinheating includes heating the bone fill material to a temperature betweenabout 45° C. and 95° C.
 24. The method of claim 22, wherein the bonefill material is mixed external to the human body.
 25. The method ofclaim 22, further comprising controlling the cooling and heating of thebone fill material to achieve a desired temperature in the bone fillmaterial.
 26. The method of claim 22, wherein the bone fill material isdelivered through an elongated introducer into a vertebral body.